Have psh have /dev/null opened as stdin instead of nothing

git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/branches/2.7@12241 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd

xCAT-client/bin/psh

@@ -6,6 +6,7 @@ BEGIN
    $::XCATROOT = $ENV{'XCATROOT'} ? $ENV{'XCATROOT'} : -d '/opt/xcat' ? '/opt/xcat' : '/usr';
 }
 close(STDIN);
+open(STDIN,"<","/dev/null");
 use lib "$::XCATROOT/lib/perl";
 use IO::Socket::SSL;
 use XML::Simple;